The numerical analysis of time-space structures in the large turning angle axial cascade with a certain large attack angle condition suffered from unsteady incoming wake excitation has been carried out.

Two-dimensional model,where the influence of wall boundary layers is neglected and inlet jet-wake velocity patterns are prescribed,was applied to simulate one vanless diffuser with large width-radius(ratio.

Assuming that the flow inside the vaneless diffuser was incompressible two dimensional flow,a state matrix model was established and analysis was made on the jet-wake type disturbance at the inlet of the diffuser based on published literatures.

The emphasis was put on the study of the effect of 8 mm diameter air bubbles arranged at different spatial positions on the rear wake flows and their interactions.